As biology 1.1-1.5 biological molecules (WATER)

• Water is composed of atoms of hydrogen and oxygen.
• One atom of oxygen combines with two atoms of hydrogen by sharing electrons ;this is covalent bonding
• The sharing of the electrons is uneven between the oxygen and hydrogen atoms
• The oxygen atom attracts the electrons more strongly than the hydrogen atoms, resulting in a weak negatively charged region on the oxygen atom (δ-) and a weak positively charged region on the hydrogen atoms (δ+ )
• The separation of charge due to the electrons in the covalent bonds being unevenly shared is called a dipole
• Polar molecule : when a molecule has one end that is negatively charged and one end that is positively charged
• Hydrogen bonds form between the positive and negatively charged regions of nearby water molecules as a result of the polar nature of water
• hydrogen bonds are weak when they are few in number, so they are constantly breaking and reforming; this means that water molecules flow past each other in a liquid state
• The polar nature of water gives water properties that make it good at transporting substances

  • Water is a solvent
  • Water is cohesive
• Hydrogen bonds between water molecules allow for strong cohesion between water molecules.
• WHAT IS COHESION

  Cohesion is the attraction of water molecules to each other
• DEFINE ADHESION.

  Water is also able to form hydrogen bonds with other molecules.
• • Water molecules pull other water molecules along due to cohesion
  • Water adheres to the sides of a vessel due to adhesion
• HOW SUBSTANCES ARE DISSOLVED IN WATER

  Water molecules surround charged particles; the positive parts of water are attracted to negatively charged particles and the negative parts of water are attracted to positively charged particles. The surrounded molecules break apart e.g. sodium chloride molecules break into sodium ions and chloride ions. The ions surrounded by water molecules have dissolved